Image capturing method and image capturing apparatus

Abstract

An image capturing method and an image capturing apparatus are provided. An inspection region image of an inspection region is captured by a first image capturing device at a first time point. A control signal is received at a second time point after the first time point. A relative translation relationship and/or a relative rotation relationship of the first image capturing device at the first time point and a second image capturing device at a second time point are calculated. A first three-dimensional coordinate value of the local region relative to the first image capturing device is calculated and the first three-dimensional coordinate value is transformed to a second three-dimensional coordinate value relative to the second image capturing device according to the relative translation relationship and the relative rotation relationship. The second image capturing device is driven to rotate. A local region image of the local region is captured.

What is claimed is: 
     
       1. An image capturing method adapted for an image capturing device, comprising:
 capturing an inspection region image of an inspection region by a first image capturing device at a first time point; 
 receiving a control signal at a second time point following the first time point, the control signal corresponding to a local region in the inspection region image; 
 calculating, by a processing unit, at least one of a relative translation relationship and a relative rotation relationship between the first image capturing device at the first time point and a second image capturing device at the second time point; 
 calculating, by the processing unit, a first three-dimensional coordinate value of the local region relative to the first image capturing device at the first time point according to the control signal, and converting the first three-dimensional coordinate value into a second three-dimensional coordinate value relative to the second image capturing device at the second time point according to at least one of the relative translation relationship and the relative rotation relationship; 
 driving, by a driving unit, the second image capturing device to rotate with a rotation amount according to the second three-dimensional coordinate value; and 
 capturing a local region image of the local region by the second image capturing device, 
 wherein the step of calculating the first three-dimensional coordinate value comprises: 
 estimating a distance between the first image capturing device at the first time point and a point in the local region along an axis perpendicular to an image plane coordinate system where the inspection region image is located as an estimated distance value; and 
 calculating the first three-dimensional coordinate value of the point in the local region relative to the first image capturing device according to the estimated distance value and a coordinate value of the point in the local region in the image plane coordinate system, 
 wherein the image capturing method further comprises an image feature matching step, comprising: 
 storing the inspection region image at the first time point by a first image temporary storage unit, and storing the local region image at the second time point by a second image temporary storage unit; and 
 determining, by the processing unit, whether an image correspondence between the inspection region image in the first image temporary storage unit and the local region image at the second time point in the second image temporary storage unit is greater than a threshold, 
 wherein the image capturing method further comprises a correction step, comprising: 
 correcting the estimated distance value by the processing unit when the image correspondence between the inspection region image in the first image temporary storage unit and the local region image at the second time point in the second image temporary storage unit is smaller than the threshold; 
 correcting the first three-dimensional coordinate value according to the corrected estimated distance value and the coordinate value of the point in the local region in the image plane coordinate system; 
 correcting the second three-dimensional coordinate value according to the corrected first three-dimensional coordinate value; and 
 determining, by the processing unit, a correction rotation amount according to the corrected second three-dimensional coordinate value, and instructing the driving unit to rotate the second image capturing device according to the correction rotation amount. 
 
     
     
       2. The image capturing method of  claim 1 , wherein the first image capturing device and the second image capturing device are mounted on a flying vehicle, and the step of calculating at least one of the relative translation relationship and the relative rotation relationship comprises:
 calculating at least one of the relative translation relationship and the relative rotation relationship according to at least one of a relative position and a relative angle of the first image capturing device and the second image capturing device on the flying vehicle and according to at least one of a translation amount and a rotation amount of the flying vehicle from the first time point to the second time point. 
 
     
     
       3. The image capturing method of  claim 2 , wherein the first image capturing device is mounted on a main body of the flying vehicle, and the second image capturing device is mounted on a self-stabilized device of the flying vehicle, the self-stabilized device is adapted to generate a compensated rotation amount according to a partial rotation amount of the main body, wherein the step of calculating at least one of the relative translation relationship and the relative rotation relationship further comprises:
 calculating at least one of the relative translation relationship and the relative rotation relationship according to the compensated rotation amount. 
 
     
     
       4. The image capturing method of  claim 1 , further comprising:
 capturing another local region image of the local region by the second image capturing device at a third time point; 
 storing the local region image by the first image temporary storage unit, and storing the another local region image by the second image temporary storage unit; 
 calculating, by the processing unit, at least one of another relative translation relationship and another relative rotation relationship between the second image capturing device at the second time point and the second image capturing device at the third time point following the second time point; 
 determining, by the processing unit, whether another image correspondence between the local region image in the first image temporary storage unit and the another local region image in the second image temporary storage unit is greater than the threshold; and 
 determining another correction rotation amount by the processing unit according to at least one of the another relative translation relationship and the another relative rotation relationship of the second image capturing device, and according to whether the another image correspondence between the local region image in the first image temporary storage unit and the another local region image in the second image temporary storage unit is greater than the threshold, and instructing the driving unit to rotate the second image capturing device according to the another correction rotation amount. 
 
     
     
       5. The image capturing method of  claim 1 , further comprising a correction step, wherein the correction step comprises:
 when the image correspondence between the inspection region image in the first image temporary storage unit and the local region image at the second time point in the second image temporary storage unit is greater than or equal to the threshold, calculating, by the processing unit, a distance from a center of a corresponding local region in the local region image to a center of the local region image to determine a correction rotation amount, and instructing the driving unit to rotate the second image capturing device according to the correction rotation amount, wherein the corresponding local region in the local region image is a region in the local region where the image correspondence is greater than or equal to the threshold. 
 
     
     
       6. The image capturing method of  claim 1 , wherein the step of calculating the first three-dimensional coordinate value comprises:
 calculating, by the processing unit, the first three-dimensional coordinate value of the local region relative to the first image capturing device according to a coordinate value of the local region in an image plane coordinate system. 
 
     
     
       7. The image capturing method of  claim 1 , wherein the control signal comprises a timestamp corresponding to the first time point and an image feature of the local region. 
     
     
       8. An image capturing apparatus, comprising:
 a first image capturing device adapted to capture an inspection region image in an inspection region at a first time point; 
 a second image capturing device; 
 a processing unit adapted to calculate at least one of a relative translation relationship and a relative rotation relationship between the first image capturing device at the first time point and the second image capturing device at a second time point, wherein the processing unit is adapted to receive a control signal at the second tune point following the first time point, the control signal corresponds to a local region in the inspection region image, and the processing unit is adapted to calculate a first three-dimensional coordinate value of the local region relative to the first image capturing device at the first time point according to the control signal and convert the first three-dimensional coordinate value into a second three-dimensional coordinate value relative to the second image capturing device at the second time point according to at least one of the relative translation relationship and the relative rotation relationship; and 
 a driving unit adapted to drive the second image capturing device to rotate with a rotation amount according to the second three-dimensional coordinate value, 
 wherein, after the driving unit drives the second image capturing device to rotate with the rotation amount, the second image capturing device is adapted to capture a local region image of the local region, 
 wherein the processing unit is adapted to estimate a distance between the first image capturing device at the first time point and a point in the local region along an axis perpendicular to an image plane coordinate system where the inspection region image is located as an estimated distance value, and is adapted to calculate the first three-dimensional coordinate value of the point in the local region relative to the first image capturing device according to the estimated distance value and a coordinate value of the point in the local region in the image plane coordinate system, 
 wherein the image capturing apparatus further comprises a first image temporary storage unit and a second image temporary storage unit, the first image temporary storage unit is adapted to store the inspection region image at the first time point, the second image temporary storage unit is adapted to store the local region image at the second time point, and the processing unit is adapted to determine whether an image correspondence between the inspection region image in the first image temporary storage unit and the local region image at the second time point in the second image temporary storage unit is greater than a threshold, 
 wherein when the image correspondence between the inspection region image in the first image temporary storage unit and the local region image at the second time point in the second image temporary storage unit is smaller than the threshold, the processing unit is adapted to correct the estimated distance value, and is adapted to correct the first three-dimensional coordinate value according to the corrected estimated distance value and the coordinate value of the point in the local region in the image plane coordinate system, and is adapted to correct the second three-dimensional coordinate value according to the corrected first three-dimensional coordinate value, and the processing unit is adapted to determine a correction rotation amount according to the corrected second three-dimensional coordinate value, and the driving unit is adapted to rotate the second image capturing device according to the correction rotation amount. 
 
     
     
       9. The image capturing apparatus of  claim 8 , comprising a flying vehicle, wherein the first image capturing device and the second image capturing device are mounted on the flying vehicle, and the processing unit is adapted to calculate at least one of the relative translation relationship and the relative rotation relationship according to at least one of a relative position and a relative angle of the first image capturing device and the second image capturing device on the flying vehicle and according to at least one of a translation amount and a rotation amount of the flying vehicle from the first time point to the second time point. 
     
     
       10. The image capturing apparatus of  claim 9 , wherein the flying vehicle comprises a main body and a self-stabilized device, the first image capturing device is mounted on the main body, and the second image capturing device is mounted on the self-stabilized device, and the self-stabilized device is adapted to generate a compensated rotation amount according to a partial rotation amount of the main body, wherein the processing unit is adapted to calculate at least one of the relative translation relationship and the relative rotation relationship according to the compensated rotation amount. 
     
     
       11. The image capturing apparatus of  claim 8 , wherein at a third time point, the second image capturing device is adapted to capture another local region image of the local region, the first image temporary storage unit is adapted to store the local region image, the second image temporary storage unit is adapted to store the another local region image, the processing unit is adapted to calculate at least one of another relative translation relationship and another relative rotation relationship between the second image capturing device and the second time point and the second image capturing device at the third time point following the second time point, the processing unit is adapted to determine whether another image correspondence between the local region image in the first image temporary storage unit and the another local region image in the second image temporary storage unit is greater than the threshold, and the processing unit is adapted to determine another correction rotation amount according to at least one of the another relative translation relationship and the another relative rotation relationship of the second image capturing device, and according to whether the another image correspondence between the local region image in the first image temporary storage unit and the another local region image in the second image temporary storage unit is greater than the threshold, and instruct the driving unit to rotate the second image capturing device according to the another correction rotation amount. 
     
     
       12. The image capturing apparatus of  claim 8 , wherein when the image correspondence between the inspection region image in the first image temporary storage unit and the local region image at the second time point in the second image temporary storage unit is greater than or equal to the threshold, the processing unit is adapted to calculate a distance from a center of a corresponding local region in the local region image to a center of the local region image to determine a correction rotation amount, and the driving unit is adapted to rotate the second image capturing device according to the correction rotation amount, wherein the corresponding local region in the local region image is a region in the local region where the image correspondence is greater than or equal to the threshold. 
     
     
       13. The image capturing apparatus of  claim 8 , wherein the processing unit is adapted to calculate the first three-dimensional coordinate value of the local region relative to the first image capturing device according to a coordinate value of the local region in an image plane coordinate system. 
     
     
       14. The image capturing apparatus of  claim 8 , wherein the control signal comprises a timestamp corresponding to the first time point and an image feature of the local region.